The recent growth in the literature on, and the devotion of an entire symposium ("Growth Regulation by Ion Fluxes", March 1979, Annals N.Y. Acad. Sci. 1980) to the control of cell proliferation by inorganic ions indicates that ions which trigger physiological responses such as muscle contraction, secretion and neurotransmitter release, are also involved in cell proliferation and neoplastic development. This proposed symposium is designed to promote the exchange of ideas and outline the prospects of this rapidly growing field. It is intended to bring together those who have contributed significantly to the basic concepts and ideas about the involvement of ions in cell proliferation and cancer. It will also encourage the participation of a limited number of others who are particularly interested in the field.